The specific objectives of this project are to relate proximate physical conditions and behaviors noted for an individual to past environmental conditions which may have occurred as far back in development as early embryogeny. In addition, this study explores interactions between current environmental conditions and previous environmental history on growth and behavior of organisms. These objectives will be accomplished using as a model an oviparious amniote vertebrate (Asian leopard gecko). The environment of these organisms will be controlled from the time of oviposit through to the adult ( a period of time less than a year). Experiments will be performed to measure post-hatching growth and adult sexual and agonistic behaviors for individuals incubated and reared at a variety of environmental conditions. The long-term objectives of this research are to provide animal models and insights for the study of mechanisms (and evolutionary origins) on non-genetic variability in development and behaviors noted in "higher" organisms (including man).